Rip -
On our boxes we run php4 compiled into apache with the optimizer and we see little difference on the server load. We did a test 6 months ago on a software site that we run, the site was getting 200K pages views a day, and was being statically called for about 90% of the pages, We switched over and added common page includes and ran it all thru php, less that 5% increase on overall system usage, and it cut down on our updating by 3 hours a day
Tim